Environmental

Other

On 29 and 30 September 1995, Oxford, England, was the electric vehicle capital of Europe. Twenty-four electric road vehicles, ranging from bicycles to vans, were performing on a city centre circuit on the occasion of the "Twelve Electric Hours", a demonstration event organised by CITELEC, the European association of cities interested in electric vehicles, in collaboration with Oxford City Council and Southern Electric.

The main aim of the "Twelve Electric Hours" was to demonstrate that electric vehicles are able to perform in daily city traffic and can be an important factor for the improvement of city traffic and more particularly for a healthier living environment. To this effect, the vehicles covered a route in the city centre during two six hour periods. Battery recharge could be performed when needed; all electricity used by the vehicle was individually metered to assess energy consumption and efficiency.

Starting point of the circuit was the Westgate Car Park, where battery charging facilities were made available by Southern Electric. The circuit was 6556 m (4.077 miles) long and consisted mainly of busy city centre streets. Passing well-known Oxford landmarks such as Christchurch, the Town Hall, Carfax, Magdalen Bridge, Broad Street and several Colleges, it confronted them directly with the city's serious traffic and pollution problems.

The importance of the event was enhanced through the parallel organisation of a conference around "Urban air quality: the benefits of electric vehicles" on 29 September; furthermore, the association CITELEC held its Executive Council and General Assembly in Oxford Town Hall on 30 September.

The results: DISTANCE

The twenty-four vehicles which took part in the event were divided into three classes: two-wheelers, cars and vans. The distances covered were measured in laps. If the last lap surpassed the six hour driving period, the actual distance covered was calculated using the average speed. Several vehicles proved able to cover more than 100 km in six hours, particularly two-wheelers, which are much less affected by traffic jams than the larger three or four wheel vehicles. Two wheelers were also the only vehicles to obtain an average speed of over 20km/hour. The vehicles which were able to reach high distances were those which could run for six hours without charging the batteries. This was the case for the vehicles fitted with advanced sodium-sulphur batteries, but also for those which came with lead-acid batteries. The results prove clearly that, contrary to some beliefs, the lead-acid battery is still a valuable energy store for urban electric vehicles and is not at all obsolete.

It is interesting to note that, except cycles, no vehicle came with nickel-cadmium batteries. This is probably due to the high cost of these batteries. For the second day, a Saturday with heavy shopping traffic, the gap between the two-wheelers and the others became even more obvious, with the four largest distances being covered by Class 1 vehicles. The combined results of the two day event is set out in Table 1.

Each participating vehicle was fitted with an individual electricity meter which measured all electricity taken up during charging of the batteries. The vehicles started the demonstration on Friday morning with a fully charged battery; after the run, all batteries had to be fully recharged again by Saturday morning to allow the full energy consumption to be measured. A classification was made, taking the energy consumption in kWh per ton.km as a reference. This allowed an equal comparison between lightweight and heavyweight vehicles. The results of the energy measurements for the first day of the event are given in Table 2.

The "12 Electric Hours of Oxford" have turned out a successful event and have proven once more the viability of electrically driven vehicles in urban traffic. An extensive press interest contributed to the public impact of the event. The presence of several key delegates from European cities assured the dissemination of the impact of this event all over Europe. Driving characteristics and performances of state-of-the-art electric vehicles are more than sufficient for their deployment in urban areas. The positive contribution these vehicles can make to the urban environment is clearly stated. Demonstration of electric and hybrid vehicles are essential to help people understand their usefulness. An event such as the "Twelve Electric Hours" gives a very good contribution to this learning process.